Dispersion-type electroluminescent element and method for manufacturing the same

ABSTRACT

A dispersion-type EL element formed on a thin or flexible transparent plastic film and a method for manufacturing the same are provided. The dispersion-type electroluminescent element is a dispersion-type electroluminescent element with at least a transparent conductive layer, a phosphor layer, a dielectric layer, and a rear electrode layer sequentially formed on a transparent plastic film surface, in which a thickness of the transparent plastic film is less than 50 μm, and the transparent conductive layer is formed by applying compression processing to an applied layer formed by applying a transparent conductive layer forming application liquid mainly composed of conductive oxide particles and a binder on the transparent plastic film surface and then, curing the compressed layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dispersion-type electroluminescentelement obtained using a film with transparent conductive layer on whicha transparent conductive layer mainly composed of conductive oxideparticles and a binder is formed and a method for manufacturing the sameand particularly to a dispersion-type electroluminescent element appliedas a light-emitting element incorporated in a key input component ofvarious devices such as a cellular phone and the like and a method formanufacturing the same.

2. Description of the Related Art

The dispersion-type electroluminescent element (hereinafter abbreviatedas “dispersion-type EL element” in some cases) is a light-emittingelement by alternating current driving and is used for a backlight andthe like of liquid crystal display in a cellular phone, a remotecontroller and the like and an application to a light emitting elementincorporated in a key input component (key pad) of various devices hasbeen recently tried as a new usage.

Such a device includes, for example, a portable information terminal andthe like such as a cellular phone, a remote controller, a PDA (PersonalDigital Assistance), a laptop PC and the like, and the light emittingelement is used with the purpose of facilitating a key input operationin a dark place such as during a night.

As the light emitting element of the key input component (key pad), alight emitting diode (LED) has been applied, but since there areproblems such that the LED is a point light source, its brightness on akey pad portion is non-uniform and its appearance is poor, white/blueluminescent colors are generally preferred but those colors take a highcost in the LED, power consumption is larger than the dispersion-type ELelement and the like, a trend to apply the dispersion-type EL elementinstead of the LED has become remarkable.

As a method for manufacturing such a dispersion-type EL element, thefollowing methods are widely employed in general. That is, it is amethod of sequentially forming a phosphor layer, a dielectric layer, anda rear electrode layer by screen printing and the like on a plastic film(hereinafter abbreviated as “sputtered ITO film”) on which a transparentconductive layer of an indium tin oxide (hereinafter abbreviated as“ITO”) is formed, using a physical film forming method such assputtering, ion-plating and the like.

Here, as a paste used for applying (printing) formation of each layer ofthe phosphor layer, dielectric layer, and the rear electrode layer,phosphor particles, dielectric particles and conductive particles aredispersed, respectively, in a solvent containing a binder, and acommercial paste, for example, may be used.

The sputtered ITO film is formed so that a ITO single layer, which is aninorganic component, is formed on a transparent plastic film ofpolyethyleneterephthalate (PET), polyethylenenaphthalate (PEN) and thelike by the above physical film forming method to have a thickness ofapproximately 20 to 50 nm, and a low resistance of approximately asurface resistivity: 100 to 300Ω/□ (ohm per square) is obtained.

However, since the ITO layer is an inorganic thin film and extremelyfragile, a micro crack (split) can occur in the film, and in order toprevent that, a plastic film to be a base material needs to be providesufficient strength and rigidity and its thickness is set at least at 50μm or more, or usually 75 μm or more.

A PET film is now widely used for the base film of the above sputteredITO film, but if its thickness is less than 50 μm, flexibility of thefilm is too high and a crack can easily occur in the ITO layer duringhandling, which extremely damages conductivity of the film. Thus, a thinsputtered ITO film with the thickness of approximately 25 μm, forexample, has not been in a practical use. In the case of a soft basefilm made of urethane and the like, even if its film thickness is 75 μmor more, it can easily have a crack when the sputtered ITO layer isformed and has not been in a practical use.

Characteristics required when the dispersion-type EL element is appliedto the keypad include, as described in Patent Document 1, for example,the above-mentioned uniformity in brightness and low power consumptionand particularly, excellence in click feeling when the key pad isoperated are important.

In order not to impair the click feeling when the dispersion-type ELelement is incorporated in the key pad, the flexibility of thedispersion-type EL element itself needs to be sufficiently improved,that is, the thickness of the element is made as thin as possible or aflexible base film needs to be used.

However, if the dispersion-type EL element is manufactured using theabove-mentioned sputtered ITO film, it is necessary to have a thicknessof at least 50 μm or more for the base film in order to prevent a crackin the ITO layer so as to improve rigidity of the film, and the flexiblebase film cannot be used. Thus, there is a problem that the clickfeeling of the key operation is not sufficiently favorable, if theelement is applied to the key pad.

As another problem different from the above, Patent Document 4, forexample, points out breakage/failure of an LCD (liquid crystal)component and the like caused by static electricity generated at a keyinput of a cellular phone. Thus, a similar problem might also occur in akey input component of the dispersion-type EL element, and as a measureagainst it, there is a method in which a transparent conductive layer isformed on an outer surface of the dispersion-type EL element, forexample so as to have the static electricity escape, but since the basefilm for the key pad has high flexibility as mentioned above, it can notbe applied to the conventional sputtered ITO film. Also, it is not easyto form an inexpensive transparent conductive film satisfying durability(hitting durability), transparency, conductivity required for the keypad on the outer surface of the dispersion-type EL element.

Patent Document 1: Japanese patent Laid-Open No. 2001-273831

Patent Document 2: Japanese patent Laid-Open No. 4-237909

Patent Document 3: Japanese patent Laid-Open No. 5-036314

Patent Document 4: Japanese patent Laid-Open No. 2002-232537

SUMMARY OF THE INVENTION

The present invention was made in view of the above conventionalcircumstances and has an object to provide a dispersion-type EL elementmore excellent in flexibility than the dispersion-type EL element usinga conventional sputtered ITO film or specifically to provide adispersion-type EL element formed on a thin or flexible transparentplastic film and a method for manufacturing the same.

In order to achieve the above object, the inventors have conductedvarious examinations and found out that in the dispersion-typeelectroluminescent elements made of at least a transparent conductivelayer, a phosphor layer, a dielectric layer, and a rear electrode layersequentially formed on a surface of a transparent plastic film, by usinga method of applying/forming the transparent conducive layer on thesurface of the transparent plastic film not by the conventional physicalfilm forming method but by using a transparent conductive layer formingapplication liquid, since the transparent conductive layer is mainlycomposed of conductive oxide particles and a binder matrix, easyoccurrence of a crack in the transparent conductive layer duringhandling of the transparent conductive film, which extremely impairs itsconductivity, can be suppressed, and by compression processing of anapplied layer obtained by applying of the application liquid for formingtransparent conductive layer, a packing density of the conductiveparticles in the transparent conductive layer is raised, scattering oflight is lowered, and optical characteristics of the film is improved.In addition, the conductivity is drastically improved, thedispersion-type EL element more excellent in conductivity andflexibility than the dispersion-type EL element using the conventionalsputtered ITO film can be provided inexpensively, and in the case ofapplying of the dispersion-type EL element to the key pad in thecellular phone and the like, favorable click feeling of a key operationcan be obtained without any special structure or devising on the keypad, which leads to the present invention.

That is, the dispersion-type electroluminescent element according to thepresent invention is characterized in that a dispersion-typeelectroluminescent element made of at least a transparent conductivelayer, a phosphor layer, a dielectric layer, and a rear electrode layersequentially formed on a transparent plastic film surface, in which athickness of the transparent plastic film is less than 50 μm and thetransparent conductive layer is obtained by applying compressionprocessing to an applied layer formed by applying a transparentconductive layer forming application liquid mainly composed ofconductive oxide particles and a binder on the transparent plastic filmsurface and then, curing the compressed layer.

Also, another dispersion-type electroluminescent element according tothe present invention is characterized in that a second transparentconductive layer is further formed on a back face (a face on which thetransparent conductive layer is not formed) of the transparent plasticfilm on which the transparent conductive layer is formed, and the secondtransparent conductive layer is obtained by applying compressionprocessing to a second applied layer formed by applying the transparentconductive layer forming application liquid mainly composed ofconductive oxide particles and a binder on the back face of thetransparent plastic film and then, curing the compressed layer, in whichthe thickness of the transparent plastic film is 25 μm or less, theconductive oxide particles contain any one or more of indium oxide, tinoxide, zinc oxide as main components, the conductive oxide particle withthe indium oxide as the main component is an indium tin oxide particle,the binder has a cross-linking performance, the transparent conductivelayer and the second transparent conductive layer have resistanceagainst organic solvent, the compression processing is conducted byrolling processing of metal rolls, the above-mentioned dispersion-typeelectroluminescent element is applied as a light emitting elementincorporated in a key input component of a device, and the device is acellular phone, a remote controller, a portable information terminal.

Moreover, the method for manufacturing the dispersion-typeelectroluminescent element according to the present invention is amethod for manufacturing a dispersion-type electroluminescent element inwhich at least a transparent conductive layer, a phosphor layer, adielectric layer, and a rear electrode layer are sequentially formed ona transparent plastic film surface, characterized in that an appliedlayer is formed on the transparent plastic film surface using atransparent conductive layer forming application liquid mainly composedof conductive oxide particles and a binder and then, compressionprocessing is conducted for the transparent plastic film on which theapplied layer is formed and then, cured so as to form the transparentconductive layer, a second applied layer is further formed on a backface (face on which the transparent conductive layer is not formed) ofthe transparent plastic film on which the transparent conductive layeris formed using the transparent conductive layer forming applicationliquid mainly composed of the conductive oxide particles and the binderand then, compression processing is conducted for the transparentplastic film on which the transparent conductive layer and the secondapplied layer are formed and then, the compressed layer is cured so asto form a second transparent conductive layer.

Also, another method for manufacturing the dispersion-typeelectroluminescent element according to the present invention is amethod for manufacturing a dispersion-type electroluminescent element inwhich at least a transparent conductive layer, a phosphor layer, adielectric layer, and a rear electrode layer are sequentially formed ona transparent plastic film surface, characterized in that an appliedlayer is formed on the transparent plastic film surface using atransparent conductive layer forming application liquid mainly composedof conductive oxide particles and a binder, second applied layer isfurther formed on a back face (face on which the applied layer is notformed) of the transparent plastic film on which the applied layer isformed using the transparent conductive layer forming application liquidmainly composed of the conductive oxide particles and the binder andthen, compression processing is conducted for the transparent plasticfilm on which the applied layer and the second applied layer are formedand then, the compressed layer is cured so as to form the transparentconductive layer and the second transparent conductive layer.

Further, another method for manufacturing the dispersion-typeelectroluminescent element according to the present invention ischaracterized in that the compression processing is conducted by rollingprocessing of metal rolls, and the rolling processing is conducted witha linear pressure 29.4 to 490 N/mm (30 to 500 kgf/cm).

Also, another method for manufacturing the dispersion-typeelectroluminescent element according to the present invention ischaracterized in that on a face opposite the face on which thedispersion-type electroluminescent element of a transparent plastic filmon which the transparent conductive layer or the transparent conductivelayer and the second transparent conductive layer are formed is formed,a release liner film (liner film that can be peeled off) on which a weakpressure-sensitive adhesive is applied is bonded and then, thedispersion-type electroluminescent element is formed and further, therelease liner film is peeled off and removed.

EFFECT OF THE INVENTION

According to the present invention, by using a method in whichdispersion-type electroluminescent element having at least a transparentplastic film and a transparent conductive layer, a phosphor layer, adielectric layer, and a rear electrode layer sequentially formed on thetransparent plastic film surface in which the transparent conductivelayer is applied and formed on the transparent plastic film surface notusing a conventional physical film forming method but using atransparent conductive layer forming application liquid, since thetransparent conductive layer is mainly composed of conductive oxideparticles and a binder matrix, easy occurrence of a crack in thetransparent conductive layer during handling of a transparent conductivefilm, which remarkably impair its conductivity, is suppressed, andmoreover, by applying compression processing to an applied layerobtained by the application of the transparent conductive layer formingapplication liquid, a packing density of the conductive particles in thetransparent conductive layer is raised, optical characteristics of afilm are improved by lowering scattering of light and moreover, theconductivity is drastically improved so that a dispersion-type ELelement more excellent in conductivity and flexibility than thedispersion-type EL element using a conventional sputtered ITO film canbe provided inexpensively. Moreover, if the above dispersion-type ELelement is applied to a key pad of a cellular phone and the like, afavorable click feeling of a key operation can be obtained without anyspecial structure or devising on the key pad, which is industriallyadvantageous.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a dispersion-type EL elementwith a basic structure according to the present invention.

FIG. 2 is a sectional view illustrating a dispersion-type EL elementwith another structure according to the present invention.

FIG. 3 is a sectional view illustrating a dispersion-type EL elementwith still another structure according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

-   1 transparent plastic film-   2 transparent conductive layer-   3 phosphor layer-   4 dielectric layer-   5 rear electrode layer-   6 collecting electrode-   7 insulating protective layer-   8 second transparent conductive layer

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The dispersion-type electroluminescent element according to the presentinvention has at least a transparent conductive layer 2, a phosphorlayer 3, a dielectric layer 4, and a rear electrode layer 5 sequentiallyformed on a transparent plastic film 1 as shown in FIG. 1.

Also, as an application to an actual device, as shown in FIG. 2, acollecting electrode 6 such as silver and the like and an insulatingprotective layer 7 are further formed for use in general.

The transparent plastic film used in the present invention preferablyhas a thickness of less than 50 μm. If the thickness of the transparentplastic film is 50 μm or more, rigidity of the film is raised, and if itis incorporated in the above-mentioned keypad as the dispersion-type ELelement, a favorable click feeling can not be obtained.

Also, if the thickness of the transparent plastic film is preferably 25μm or less, or more preferably 16 μm or less, a further favorable clickfeeling can be obtained, and since the total thickness of thedispersion-type EL element can be made as thin as 100 μm or less, forexample, it is also preferable in a point that freedom in designing thedevice is improved.

Moreover, a material of the transparent plastic film is not particularlylimited but various plastics can be used. Specifically, plastics such aspolycarbonate (PC), polyethersulphone (PES), polyethyleneterephthalate(PET), polyethylenenaphthalate (PEN), polyethylene (PE), polypropylene(PP), urethane, nylon, fluorine resin and the like can be used but amongthem, use of a PET film is preferable from the viewpoint of itsexcellence in price, transparency, strength, and flexibility and thelike.

In the dispersion-type EL element according to the present invention, asshown in FIG. 3, a second transparent conductive layer 8 may be furtherformed on a face (back face) opposite the face on which the transparentconductive layer 2 is formed on the transparent plastic film 1.

The second transparent conductive layer has a purpose of preventingvarious adverse effects caused by static electricity and its resistancevalue may be much higher than the resistance value of theabove-mentioned transparent conductive layer applied as an electrode ofthe dispersion-type EL element, and the value is preferablyapproximately 1M(1×10⁶)Ω/□ or less, for example.

The second transparent conductive layer is formed by forming a secondapplied layer by applying a transparent conductive layer formingapplication liquid in which conductive oxide particles are dispersed ina solvent containing a binder component on a transparent plastic filmand then, compression processing applied to the second applied layer andthen the compressed layer is cured, but from the viewpoint of preventinga drop of brightness of the dispersion-type EL element as much aspossible, it preferably has a high transmittance, and thus, the filmthickness is preferably 3 μm or less, or more preferably 1 μm or less.

A material of the binder used in the second transparent conductive layeris not particularly limited as long as it has a favorable adhesion withthe transparent plastic film and has transparency and predeterminedconductivity, and various resins may be used. Specifically, resins suchas urethane, epoxy, polyester, fluorine resins and the like may be used.Among them, urethane and fluorine resins are preferable from theviewpoint of excellence in price, transparency, strength and flexibilityand the like.

The transparent conductive layer mainly composed of the conductive oxideparticles and the binder matrix formed on the transparent plastic filmsurface can be obtained by applying and drying using the transparentconductive layer forming application liquid in which the conductiveoxide particles dispersed in the solvent containing the binder componenton the transparent plastic film, and then, by applying compressionprocessing to it together with the transparent plastic film and thecuring the binder component.

The film (applied layer) before the compression processing obtained byapplying and drying the transparent conductive layer forming applicationliquid is in a state where a large number of micro voids are formedbetween the conductive particles and the binder matrix. The voids aregenerated because a mixed amount of the binder component is small in thetransparent conductive layer forming application liquid of the presentinvention (in the case of the conductive particles/bindercomponent=90/10, for example), and close-packing of the conductiveparticles is difficult only by applying and drying the transparentconductive layer forming application liquid, and considerable voids aregenerated between the conductive particles and they can not becompletely filled by the binder component.

Here, as the compression processing, the transparent plastic film havingthe applied layer on which the transparent conductive layer formingapplication liquid is applied/dried may be rolled by steel rolls, forexample. In the present invention, the dispersion-type EL element isfinally obtained with a structure having a rolling-processed transparentconductive layer on an extremely thin transparent plastic film surface,but in the rolling processing process, the rolling processing needs tobe carried out carefully because a thin transparent plastic film isused, and a linear pressure of the rolling pressure of the steel rollsis preferably 29.4 to 784 N/mm (30 to 800 kgf/cm), more preferably 98 to490 N/mm (100 to 500 kgf/cm), and further preferably 196 to 294 N/mm(200 to 300 kgf/cm). If the linear pressure is less than 29.4 N/mm (30kgf/cm), an effect of improving the resistance value of the transparentconductive layer by the rolling processing is not sufficient, while ifthe linear pressure exceeds 784 N/mm (800 kgf/cm), a rolling facilitywould become large and the transparent plastic film might be distorted.Considering a price of the rolling facility and a balance among thecharacteristics of the transparent conductive layer by the rollingprocessing (transmittance, haze, resistance value), the value ispreferably set as appropriate in a range of 98 to 490 N/mm (100 to 500kgf/cm).

The rolling pressure (N/mm²) in the rolling processing of the steelrolls is a value obtained by dividing a linear pressure by a nip width(width compressed by the steel rolls). The nip width is approximately0.7 to 2 mm for a diameter of approximately 150 mm, though it depends ona diameter and a linear pressure of the steel rolls.

By the rolling processing, the packing density of the conductiveparticles in the transparent conductive layer can be improved toapproximately a low value of 45 vol % or less to as high as 50 to 80 vol% (preferably 55 to 80%), for example, though it depends on the linearpressure as compared with the case without carrying out the rollingprocessing. The packing density exceeding 80 vol % seems to be difficultto be achieved, considering presence of the binder component containedin the transparent conductive layer forming application liquid and aphysical filling structure of the conductive particles.

By carrying out such rolling processing, since the voids present in thefilm are shrunk and lost and the packing density of the conductiveparticles in the transparent conductive layer is raised, not only thatthe scattering of light is lowered and the optical characteristics ofthe film are improved but that the conductivity can be drasticallyraised.

The transparent plastic film is preferably applied withadhesion-promoting treatment, or specifically, primer treatment, plasmatreatment, corona discharge treatment, short-wavelength ultravioletirradiation treatment, silane coupling treatment and the like inadvance.

The conductive oxide particles used in the transparent conductive layerforming application liquid are conductive oxide particles mainlycomposed of any one or more of indium oxide, tin oxide and zinc oxideand include, for example, indium tin oxide (ITO) particle, indium zincoxide (IZO) particle, indium-tungsten oxide (IWO) particle,indium-titanium oxide (ITiO) particle, indium zirconium oxide particle,tin antimony oxide (ATO) particle, fluorine tin oxide (FTO) particle,aluminum zinc oxide (AZO) particle, gallium zinc oxide (GZO) particleand the like but not limited to them as long as transparency andconductivity are provided.

However, among them, ITO has the highest characteristics in a point thatit has both a high visible-light transmittance and an excellentconductivity and it is preferable.

An average particle size of the conductive oxide particle is preferably1 to 500 nm, and more preferably 5 to 100 nm. If the average particlesize is less than 1 nm, manufacture of the ¥ transparent conductivelayer forming application liquid is difficult and a resistance value ofthe obtained transparent conductive layer is high. On the other hand, ifthe size exceeds 500 nm, the conductive oxide particles easily sedimentsin the transparent conductive layer forming application liquid and itshandling becomes difficult, and simultaneous achievement of both a hightransmittance and a low resistance value in the transparent conductivelayer becomes difficult.

The size of 5 to 100 nm is more preferable because it becomes possibleto provide both the characteristics (transmittance, resistance value) ofthe transparent conductive layer and stability (sediment of theconductive particles) and the like of the transparent conductive layerforming application liquid in a well-balanced manner.

The average particle size of the conductive oxide particles is indicatedby a value observed by a transmission electron microscope (TEM).

The binder component of the transparent conductive layer formingapplication liquid has a function to bind the conductive oxide particlestogether and to improve conductivity and strength of the film, afunction to improve adhesion between the transparent plastic film andthe transparent conductive layer, and a function to impart solventresistance in order to prevent deterioration of the transparentconductive layer caused by an organic solvent contained in variousprinting pastes used for forming of the phosphor layer, dielectriclayer, rear electrode layer and the like in a manufacturing process ofthe dispersion-type EL element. As the binder, an organic and/or aninorganic binder may be used and selected as appropriate, consideringthe transparent plastic film to which the transparent conductive layerforming application liquid is applied and film forming conditions andthe like of the transparent conductive layer so that the above roles aresatisfied.

To the above organic binder, thermoplastic resins such as acrylic resin,polyester resin and the like may be applied, but the binder preferablyhas solvent resistance in general, and for that purpose, it should be across-linkable resin, and it can be selected from thermosetting resin,cold-setting resin, ultraviolet-curable resin, electron-beam curableresin and the like. For example, the thermosetting resins include epoxyresin, fluorine resin and the like, the cold-setting resins includetwo-component epoxy resin, urethane resin and the like, theultraviolet-curable resins include resins containing various oligomers,monomers, and photoinitiator and the like, and the electron-beam curableresins include resins containing various oligomers and monomers and thelike but not limited to these resins.

The inorganic binders include binders mainly composed of silica sol,alumina sol, zirconia sol, titania sol and the like. For example, as thesilica sol, a polymer obtained by adding water and acid catalyst totetra-alkyl silicate for hydrolysis and dehydropolycondensation is madeto progress or a polymer obtained by commercial alkyl silicate solutionwhich has been already polymerized to tetramer to pentamer is furthersubjected to hydrolysis and dehydropolycondensation and the like may beused.

If the dehydropolycondensation has progressed too much, solutionviscosity is raised and solidified in the end, and a degree ofdehydropolycondensation is adjusted to an upper limit viscosity or lessthat can be applied on a transparent substrate. However, the degree ofdehydropolycondensation is not particularly limited as long as it is alevel not more than the above upper-limit viscosity, but consideringfilm strength, weather resistance and the like, approximately 500 to50000 in a weight-average molecular weight is preferable. Then, thealkyl silicate hydrolyzed polymer (silica sol) substantially completesdehydropolycondensation reaction (cross-linking reaction) at heatingafter applying and drying of the transparent conductive layer formingapplication liquid and becomes a hard silicate binder matrix (bindermatrix mainly composed of silicon oxide). The dehydropolycondensationreaction starts immediately after drying of the film and as timeelapses, the reaction solidifies the conductive oxide particles togetherfirmly enough to an extent that they can not move, and if the inorganicbinder is used, the above-mentioned compression processing needs to beconducted as soon as possible after applying and drying of thetransparent conductive layer forming application liquid.

As the binder, an organic-inorganic hybrid binder may be used. Forexample, such binders include a binder obtained by modifying theabove-mentioned silica sol with partially organic functional group and abinder mainly composed of various coupling agents such as a silanecoupling agent and the like.

The transparent conductive layer using the above inorganic binder or theorganic-inorganic hybrid binder inevitably has an excellent solventresistance but it should be selected as appropriate so that adhesionwith the transparent plastic film and flexibility of the transparentconductive layer and the like are not deteriorated.

A ratio between the conductive oxide particles and the binder componentin the transparent conductive layer forming application liquid is,supposing that specific gravities of the conductive oxide particles andthe binder components are approximately 7.2 (specific gravity of ITO)and approximately 1.2 (specific gravity of usual organic resin binder),respectively, in a weight ratio, is such that the conducive oxideparticle: binder component=85:15 to 97:3, or preferably 87:13 to 95:5.The reason is that in the case of the rolling processing of the presentinvention, if the binder component is larger than 85:15, resistance ofthe transparent conductive layer becomes too high, while if the bindercomponent is smaller than 97:3 on the contrary, strength of thetransparent conductive layer is lowered and sufficient adhesion with thetransparent plastic film can not be obtained.

The method for manufacturing the transparent conductive layer formingapplication liquid used in the present invention will be described.First, after the conductive oxide particles are mixed with a solvent anda dispersing agent as necessary, dispersing processing is applied so asto obtain a liquid with conductive oxide particles dispersed. As thedispersing agent, various coupling agents such as a silane couplingagent and the like, various polymer dispersing agents, varioussurfactants such as anionic, nonionic, cationic and the like can becited. These dispersing agents can be selected as appropriate accordingto the type of the conductive oxide particle in use and dispersingprocessing method applied.

Alternatively, even if no dispersing agent is used at all, depending ona combination of the conductive oxide particle and the solvent to beapplied and the dispersing method, a favorable dispersing state can beobtained in some cases. Since the use of the dispersing agent mightdeteriorate the resistance value of the film or weather resistance, thetransparent conductive layer forming application liquid without usingthe dispersing agent is the most preferable. As the dispersingprocessing, general-purpose methods such as ultrasonic processing,homogenizer, paint shaker, beads mill and the like may be applied.

By adding the binder component to the obtained liquid with conductiveoxide particles dispersed, and moreover, by applying componentadjustment of the conductive oxide particle concentration, solventcomposition and the like, the transparent conductive layer formingapplication liquid is obtained. Here, the binder component is added tothe liquid with conductive oxide particles dispersed, but it may beadded in advance before the dispersing process of the conductive oxideparticles and there is no particular restriction. The conductive oxideparticle concentration may be set as appropriate according to theapplying method(coating method) to be used.

A solvent used for the transparent conductive layer forming applicationliquid is not particularly limited but may be selected as appropriatedepending on the applying method(coating method), film formingconditions, and a material of the transparent plastic film. For example,they include water, alcohol solvents such as methanol (MA), ethanol(EA), 1-propanol (NPA), isopropanol (IPA), butanol, pentanol, benzylalcohol, diacetone alcohol (DAA) and the like, ketone solvents such asacetone, methyl ethyl ketone (MEK), methyl propyl ketone, methylisobutyl ketone (MIBK), cyclohexanone, isophorone and the like, estersolvents such as ethyl acetate, butyl acetate, methyl lactate and thelike, glycol derivatives such as ethylene glycol monomethyl ether (MCS),ethylene glycol monomethyl ether (ECS), ethylene glycol isopropyl ether(IPC), ethylene glycol monobutyl ether (BCS), ethylene glycol monoethylether acetate, ethylene glycol monobutyl ether acetate, propylene glycolmonomethyl ether (PGM), propylene glycol ethyl ether (PE), propyleneglycol methyl ether acetate (PGM-AC), propylene glycol ethyl etheracetate (PE-AC), diethylene glycol monomethyl ether, diethylene glycolmonoethyl ether, diethylene glycol monobutyl ether, diethylene glycolmonomethyl ether acetate, diethylene glycol monoethyl ether acetate,diethylene glycol monobutyl ether acetate, diethylene glycol dimethylether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether,dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether,dipropylene glycol monobutyl ether and the like, benzene derivativessuch as toluene, xylene, mesitylene, dodecyl benzene and the like,formamide (FA), N-methyl formamide, dimethyl formamide (DMF), dimethylacetamide, dimethyl sulfoxide (DMSO), N-methyl-2-pyrolidone (NMP),γ-butyrolactone, ethylene glocol, diethylene glycol, tetrahydrofuran(THF), chloroform, mineral spirits, terpineol and the like, but notlimited to them.

Next, a method for manufacturing the dispersion-type electroluminescentelement according to the present invention will be described.

First, using the above transparent conductive layer forming applicationliquid, an applied layer is formed by applying and drying it on atransparent plastic film by a method such as screen printing, bladecoating, wire-bar coating, spray coating, roll coating, gravure printingand the like and then, the above-mentioned compression processing isapplied. The compression processing is preferably carried out by therolling processing of metal rolls. After that, the applied layer whichwas applied with the compression processing is subjected to curingprocessing such as drying curing, heat curing, ultraviolet curing andthe like according to the type of the application liquid so as to formthe transparent conductive layer.

Also, prior to forming the above transparent conductive layer, at thesame time or after that, as necessary, on the other face (back face) onwhich the transparent conductive layer of the transparent plastic filmis not formed, using the transparent conductive layer formingapplication liquid mainly composed of the conductive oxide particles andthe binder, a second applied layer is formed by applying and drying by amethod similar to the above and then, the second applied layer only ortogether with the above applied layer or the above transparentconductive layer, the above-mentioned compression processing is appliedand then, the compression layer is cured so that the second transparentconductive layer can be formed.

The term “applied layer” in the present description is used with ameaning of a film obtained by applying and drying the transparentconductive layer forming application liquid, and the term “transparentconductive layer” is used with a meaning of a film finally obtained byusing the transparent conductive layer forming application liquid.Therefore, the “transparent conductive layer” is used clearly separatelyfrom the “applied layer” of the transparent conductive layer formingapplication liquid.

The phosphor layer, the dielectric layer, and the rear electrode layerformed on the transparent conductive layer can be formed sequentially bythe screen printing and the like. As a paste for applying(printing) andforming each layer of the phosphor layer, the dielectric layer, and therear electrode layer, a commercially available paste can be used. Thephosphor layer paste and the dielectric layer paste are obtained bydispersing phosphor particles and dielectric particles in a solventcontaining a binder mainly composed of a fluorine rubber, respectively,and the rear electrode layer paste is obtained by dispersing conductiveparticles such as carbon particles and the like in a solvent containinga thermosetting resin binder.

Here, in forming the dispersion-type electroluminescent element byscreen printing of the phosphor layer and the like on the transparentconductive layer, a release liner film (liner film that can be peeledoff) in which a weak pressure-sensitive adhesive is applied on a thintransparent plastic film with the transparent conductive layer formedmay be bonded so as to reinforce its strength. That is because since thethickness of the transparent plastic film is as thin as less than 50 μm,when each of the phosphor layer, the dielectric layer, and the rearelectrode layer is printed on it as it is, not only that handling is noteasy but the following problems might occur in the screen printing. Thatis, in the screen printing in general, using a suction stage with alarge number of small-diameter holes, a pressure of the hole portion isreduced so as to fix the film, but if the film is thin, the film on thehole portion is deformed and hollowed due to the pressure reduction,which causes a trace of this hollow on the screen-printed film. By usinga porous member at the suction stage, the above problem can beprevented, but since the device price is raised by that, it is notwidely used in general. If the release liner film is bonded as mentionedabove, rigidity of the film is raised and the above hollow is notcaused, and uniformity of the printing is not impaired. The releaseliner film can be easily peeled off and removed after the manufacture ofthe dispersion-type EL element.

Since the transparent plastic film and the above release liner used inthe present invention prevent shrinkage (dimensional change) and curlingof the film by the heating processing in the manufacturing process ofthe dispersion-type EL element, they are preferably subjected to theheating processing at 130 to 150° C. in advance, which is a heatprocessing temperature of the manufacturing process of thedispersion-type EL element.

Major portions of the dispersion-type EL element are constituted by theabove transparent conductive layer, the phosphor layer, the dielectriclayer, and the rear electrode layer, but in the actual dispersion-typeEL element, a collecting electrode (formed by silver paste) of thetransparent conductive layer, a lead electrode (formed by silver paste)of the rear electrode layer, insulating protective coating (formed byinsulating paste) for preventing short-circuit between electrodes,electric shock and the like are further formed.

The dispersion-type electroluminescent element of the present inventionis excellent in flexibility as a dispersion-type EL element since thethickness of the transparent plastic film, which is a base film, isthin, and the element is applied as a light emitting element to beincorporated in a key input component of a device and enables obtainmentof a favorable click feeling of a key operation without any specialstructure or devising of the key pad. Therefore, the element can beapplied as a light emitting element to be incorporated in the key inputcomponent of a device such as a cellular phone, a remote controller, aportable information terminal and the like.

Examples of the present invention will be specifically described below,but the present invention is not limited to the examples. Also, the “%”in the text indicates “weight %” except for “%” of transmittance andhaze value and a “part” indicates a “part by weight”.

Example 1

Granular ITO particles with an average particle size of 0.03 μm (productname: SUFP-HX, by Sumitomo Metal Mining Co., Ltd.) in 36 g, methylisobutyl ketone (MIBK) as a solvent in 24 g, and cyclohexanone as asolvent in 36 g are mixed and applied with dispersing processing andthen, urethane acrylate ultraviolet-curable resin binder in 3.8 g and aphotoinitiator (Darocur 1173) in0.2 g are added and agitatedwell soas toobtain an transparent conductive layer forming application liquid inwhich the ITO particles with an average dispersed particle size of 130nm are dispersed.

On one face of a PET film (by Teijin Limited, thickness of 25 μm) as atransparent plastic film, corona discharge treatment asadhesion-promoting treatment is applied and then, the transparentconductive layer forming application liquid is wire-bar-coated (wirediameter: 0.15 mm) and dried at 60° C. for one minute. Then, applyingrolling processing by hard-chromium-plated steel rolls with a diameterof 100 mm (linear pressure: 200 kgf/cm=196 N/mm, nip width: 0.8 mm), thebinder component is further cured (in nitrogen, 100 mW/cm^(2×2) seconds)by a high-pressure mercury lamp so as to form a transparent conductivelayer (film thickness: 1.0 μm) constituted by the ITO particles and thebinder closely packed on the PET film. The packing density of theconductive particles in the transparent conductive layer after therolling processing is approximately 60 vol %.

As for the transparent plastic film, in order to prevent shrinkage(dimensional change) and curling of the film by the heating processingin the manufacturing process of the dispersion-type EL element, whichwill be described later, the heating processing at 130° C.×60 minutes isapplied in advance, and then, the transparent conductive layer is formedon it.

The film characteristics of the transparent conductive layer arevisible-light transmittance: 92.0%, haze value: 2.0%, surfaceresistivity: 525Ω/□. Since the surface resistivity is subjected toinfluence of ultraviolet irradiation at the binder curing and tends tolower temporarily immediately after the curing, measurement is made oneday after the formation of the transparent conductive layer.

The transmittance and the haze value of the above-mentioned transparentconductive layer are the values only of the transparent conductive layerand acquired by the following calculation formulas 1 and 2,respectively:

Transmittance of the transparent conductive layer (%)=[(transmittancemeasured for the transparent plastic film on which the transparentconductive layer is formed)/transmittance of the transparent plasticfilm]×100  [Calculation formula 1]

Haze value of the transparent conductive layer (%)=(haze value measuredfor the transparent plastic film on which the transparent conductivelayer is formed)−(haze value of the transparent plasticfilm)  [Calculation formula 2]

The surface resistivity of the transparent conductive layer is measuredby using a surface resistivity meter Loresta-AP (MCP-T400) by MitsubishiChemical Corporation. The haze value and the visible-light transmittanceare measured by using a haze meter (HR-200) by Murakami Color Researchlaboratory Co., Ltd.

Next, on the PET film on which the transparent conductive layer isformed, a phosphor paste (by Dupont, 7154J) in which zinc sulfideparticles, which are phosphor, are dispersed in a resin solution mainlycomposed of fluorine polymer is made, screen printing with a size of 4×5cm using a 200-mesh polyester screen is applied, and it is dried at 120°C.×30 minutes so as to form the phosphor layer. Fixation of thetransparent plastic film at the screen printing is made by a poroussuction plate.

On the above phosphor layer, a dielectric paste (by Dupont, 7153) inwhich barium titanate particles are dispersed in a resin solution mainlymade of fluorine polymer is prepared, screen printing with a size of 4×5cm using a 200-mesh polyester screen is applied, and it is dried (120°C.×30 minutes), such a screen printing step and drying step are repeatedtwice so as to form the dielectric layer.

On the dielectric layer, a carbon conductive paste (by Fujikura KaseiCo., Ltd., FEC-198) is screen-printed witha size of 3.5×4.5 cm using a200-mesh polyester screen, and it is driedat 130° C.×30 minutes soas toform a rear electrode layer.

On one ends of the transparent conductive layer and the rear electrodelayer, an Ag lead forvoltage application is formed using a silverconductive paste so as to have a dispersion-type EL element according toExample 1. In order toprevent short-circuit between electrodes, electricshock and the like, as insulating protective coating of the transparentconductive layer and the rear electrode layer, an insulating layer isformed using an insulating paste (by Fujikura Kasei Co., Ltd., XB-101G)as necessary, but since it is not a portion relating to the essentialsof the present invention, the details are omitted.

When a voltage of 100V, 400 Hz is applied to between the leads forvoltage application of the above dispersion-type EL element, thedispersion-type EL element uniformly emits light and its brightnessmeasurement shows 53 Cd/m². The brightness is measured by a brightnessmeter (by Topcon Corporation, product name: BM-9).

Example 2

In Example 1, using the PET film with a thickness of 16 μm as thetransparent plastic film, the transparent conductive layer (filmthickness: 1.0 μm) constituted by the ITO particles and the binderclosely packed on the PET film is formed. The packing density of theconductive particles in the transparent conductive layer after therolling processing is approximately 60 vol %.

As for the transparent plastic film, similarly to Example 1, in order toprevent shrinkage (dimensional change) and curling of the film by theheating processing in the manufacturing process of the dispersion-typeEL element, the heating processing at 130° C.×60 minutes is applied inadvance, and then, the transparent conductive layer is formed on it.

The transparent conductive layer has visible-light transmittance: 92.2%,haze value: 1.8%, surface resistivity: 490Ω/□. The conditions other thanthem are similar to those of Example 1 so as to obtain thedispersion-type EL element according to Example 2.

When a voltage of 100V, 400 Hz is applied to between the leads forvoltage application of the above dispersion-type EL element, thedispersion-type EL element uniformly emits light and its brightnessmeasurement shows 52 Cd/m².

Example 3

In Example 2, on the face on which the transparent conductive layer ofthe PET film with the thickness of 16 μm with the transparent conductivelayer is not formed, a release liner (liner film that can be peeled off)on which a heat resistant silicone weak pressure-sensitive adhesive isapplied on the PET film with the thickness of 100 μm is bonded, andsimilarly to Example 2 except that a suction fixing plate having a largenumber of holes of approximately 0.5 to 1 mm is used at the screenprinting of the manufacturing process of the dispersion-type EL element,the dispersion-type EL element according to Example 3 is obtained bypeeling off the release liner after the dispersion-type EL elementmanufacturing process is finished.

In order to prevent shrinkage (dimensional change) and curling of thefilm by the heating processing in the manufacturing process of thedispersion-type EL element, the release liner is used after the heatingprocessing at 130° C.×60 minutes is applied in advance.

When a voltage of 100V, 400 Hz is applied to between the leads forvoltage application of the above dispersion-type EL element, thedispersion-type EL element uniformly emits light and its brightnessmeasurement shows 52 Cd/m².

Example 4

On both faces of a PET film with a thickness of 16 μm as a transparentplastic film, corona discharge treatment as adhesion-promoting treatmentis applied and then, the transparent conductive layer formingapplication liquid in Example 1 is wire-bar-coated (wire diameter: 0.075mm) on one of the faces and dried at 60° C. for one minute and moreover,on the face opposite to the transparent plastic film, the transparentconductive layer forming application liquid is wire-bar-coated (wirediameter: 0.15 mm) and dried at 60° C. for one minute so as to obtain atransparent plastic film in which a dried coating film (applied layerand second applied layer) of the transparent conductive layer formingapplication liquid is formed on both surfaces. Then, rolling processingby hard-chromium-plated steel rolls with a diameter of 100 mm (linearpressure: 200 kgf/cm=196 N/mm, nip width: 0.8 mm) is applied to thistransparent plastic film, the binder component is further cured (innitrogen, 100 mW/cm²×2 seconds) by a high-pressure mercury lamp so as toform a transparent conductive layer (film thickness: 1.0 μm) and asecond transparent conductive layer (film thickness: 0.4 μm) on the bothfaces of the PET film constituted by the ITO particles and the binderclosely packed. The packing density of the conductive particles in thetransparent conductive layer after the rolling processing isapproximately 60 vol %.

As for the transparent plastic film, in order to prevent shrinkage(dimensional change) and curling of the film by the heating processingin the manufacturing process of the dispersion-type EL element, whichwill be described later, the heating processing at 130° C.×60 minutes isapplied in advance, and then, the transparent conductive layer is formedon it.

The film characteristics of the transparent conductive layer (theoptical characteristics include those of the transparent conductivelayer and the second transparent conductive layer) are visible-lighttransmittance: 88.5%, haze value: 3.6%, surface resistivity of thetransparent conductive layer with the film thickness: 1.0 μm being545Ω/□, while surface resistivity of the second transparent conductivelayer with the film thickness: 0.4 μm being 1300Ω/□. Since the surfaceresistivity is subjected to influence of ultraviolet irradiation at thebinder curing and tends to lower temporarily immediately after thecuring, measurement is made one day after the formation of thetransparent conductive layer.

On the transparent conductive layer with the film thickness: 1.0 μm,each layer is laminated similarly to Example 1 so as to obtain adispersion-type EL element according to Example 4 having a secondtransparent conductive layer on the outer surface.

When a voltage of 100V, 400 Hz is applied to between the leads forvoltage application of the above dispersion-type EL element, thedispersion-type EL element uniformly emits light and its brightnessmeasurement shows 50 Cd/m².

Comparative Example 1

In Example 1, in the process for forming the transparent conductivelayer, the transparent conductive layer (film thickness: 1.3 μm)constituted by the ITO particles and the binder not packed closely onthe PET film is formed without conducting the rolling processing (linearpressure: 200 kgf/cm=196 N/mm). The packing density of the conductiveparticles in this transparent conductive layer is approximately 45 vol%.

The film characteristics of the transparent conductive layer arevisible-light transmittance: 83.9%, haze value: 17.3%, surfaceresistivity: 15 KΩ/□. Since the surface resistivity is subjected toinfluence of ultraviolet irradiation at the binder curing and tends tolower temporarily immediately after the curing, measurement is made oneday after the formation of the transparent conductive layer.

With the process similar to Example 1 except that the transparentplastic film on which the transparent conductive layer is formed isused, the dispersion-type EL element according to Comparative Example 1is obtained.

When a voltage of 100V, 400 Hz is applied to between the leads forvoltage application of the above dispersion-type EL element, lightemission of the dispersion-type EL element is non-uniform and there is aportion with an extremely low brightness as approximately 30 Cd/m².

Comparative Example 2

In Example 1, using the PET film with the thickness of 100 μm as thetransparent plastic film, the transparent conductive layer (filmthickness: 1.0 μm) constituted by the ITO particles and the binderclosely packed on the PET film is formed. The packing density of theconductive particles in the transparent conductive layer after therolling processing is approximately 57 vol %.

The transparent conductive layer have visible-light transmittance:92.0%, haze value: 2.2%, surface resistivity: 625Ω/□, Similarly toExample 1 except the above, the dispersion-type EL element according toComparative Example 2 is obtained.

When a voltage of 100V, 400 Hz is applied to between the leads forvoltage application of the above dispersion-type EL element, thedispersion-type EL element uniformly emits light and its brightnessmeasurement shows 53 Cd/m².

Comparative Example 3

In Comparative Example 2, similarly to Example 1 except that instead ofthe PET film having the transparent conductive layer constituted by theITO particles and the binder closely packed, a commercially availablesputtered ITO film (visible-light transmittance: 92.0%, haze value: 0%,surface resistivity: 100Ω/□) in which the ITO layer is formed on the PETfilm (base film) with the thickness of 125 μm by sputtering method isused, the dispersion-type EL element according to Comparative Example 3is obtained.

When a voltage of 100V, 400 Hz is applied to between the leads forvoltage application of the above dispersion-type EL element, thedispersion-type EL element uniformly emits light and its brightnessmeasurement shows 55 Cd/m².

The transmittance and the haze value of the above-mentioned sputteredITO film are the values only of the ITO layer and acquired,respectively, by the following calculation formulas 3 and 4:

Transmittance of the ITO layer (%)=[(transmittance measured for the basefilm on which the ITO layer is formed)/transmittance of the basefilm]×100  [Calculation formula 3]

Haze value of the ITO layer (%)=(haze value measured for the base filmon which the ITO layer is formed)−(haze value of the basefilm)  [Calculation formula 4]

[Flexibility Evaluation of Dispersion-type EL Element]

After the dispersion-type EL element according to each Example and eachComparative Example is wound around a rod with a diameter of 3 mm onceeach so that its light emitting face is faced inward and outward,respectively, a voltage of 100V, 400 Hz is applied to between the leadsfor voltage application of the dispersion-type EL element and a lightemitting state of the element is observed. In each Example, no change isfound in the light emitting state. With Comparative Example 2, becausethe thickness of the PET film as base material is as thick as 100 μm, itis difficult to wind it around the rod with the diameter of 3 mm, andwhen it is forced, a peeled-off portion is caused in apart of theelement, which makes the light emission non-uniform. With ComparativeExample 3, a crack is caused in the sputtered ITO layer, and almost nolight is emitted from the element. Since Comparative Example 1originally has non-uniform light emission, evaluation is not made.

[Solvent Resistance Evaluation of Transparent Conductive Layer]

In each Example, after the transparent conductive layer is formed on thesurface of the transparent plastic film, the transparent conductive faceis rubbed by a cotton swab dipped with acetone reciprocally ten timesand the change in appearance is observed, but no change is found at all.The dispersion-type EL element is made using the evaluated transparentconductive layer and a voltage of 100V, 400 Hz is applied to between theleads for voltage application and the light emitting state of theelement is observed, but light emission is uniform, including theportion rubbed by the cotton swab, and no influence by acetone is found.

1. A dispersion-type electroluminescent element made of at least atransparent conductive layer, a phosphor layer, a dielectric layer, anda rear electrode layer sequentially formed on a transparent plastic filmsurface, characterized in that a thickness of said transparent plasticfilm is less than 50 μm and said transparent conductive layer isobtained by applying compression processing to an applied layer formedby applying a transparent conductive layer forming application liquidmainly composed of conductive oxide particles and a binder on thetransparent plastic film surface and then, curing the compressed layer.2. The dispersion-type electroluminescent element according to claim 1,wherein on a back face (face on which the transparent conductive layeris not formed) of said transparent plastic film on which saidtransparent conductive layer is formed, a second conductive layer isfurther formed, and said second transparent conductive layer is obtainedby applying compression processing to a second applied layer formed byapplying a transparent conductive layer forming application liquidmainly composed of conductive oxide particles and a binder on the backface of the transparent plastic film and then, curing the compressedlayer.
 3. The dispersion-type electroluminescent element according toclaim 1, wherein a thickness of said transparent plastic film is 25 μmor less.
 4. The dispersion-type electroluminescent element according toclaim 1, wherein said conductive oxide particles contain any one or moreof indium oxide, tin oxide, and zinc oxide as its main component.
 5. Thedispersion-type electroluminescent element according to claim 4, whereinthe conductive oxide particles mainly composed of said indium oxide isindium tin oxide particles.
 6. The dispersion-type electroluminescentelement according to claim 1, wherein said binder is cross-linkable, andsaid transparent conductive layer and a second transparent conductivelayer have resistance against organic solvent.
 7. The dispersion-typeelectroluminescent element according to claim 1, wherein saidcompression processing is conducted by rolling processing of metalrolls.
 8. A dispersion-type electroluminescent element characterized inthat the dispersion-type electroluminescent element according to claim 1is applied as a light emitting element incorporated in a key inputcomponent of a device.
 9. The dispersion-type electroluminescent elementaccording to claim 8, wherein said device is a cellular phone, a remotecontroller, a portable information terminal.
 10. A method formanufacturing a dispersion-type electroluminescent element in which atleast a transparent conductive layer, a phosphor layer, a dielectriclayer, and a rear electrode layer are sequentially formed on a surfaceof a transparent plastic film, characterized in that an applied layer isformed by using a transparent conductive layer forming applicationliquid mainly composed of conductive oxide particles and a binder onsaid transparent plastic film surface and then, the transparent plasticfilm on which the applied layer is formed is applied with compressionprocessing and then cured so as to form the transparent conductivelayer.
 11. The method for manufacturing a dispersion-typeelectroluminescent element according to claim 10, wherein on a back face(face on which the transparent conductive layer is not formed) of saidtransparent plastic film on which said transparent conductive layer isformed, a second applied layer is further formed by using an transparentconductive layer forming application liquid mainly composed ofconductive oxide particles and a binder, and then, a second transparentconductive layer is formed by applying compression processing to thetransparent plastic film on which the transparent conductive layer andthe second applied layer are formed and then, curing the compressedlayer.
 12. A method for manufacturing a dispersion-typeelectroluminescent element in which at least a transparent conductivelayer, a phosphor layer, a dielectric layer, and a rear electrode layerare sequentially formed on a surface of a transparent plastic film,characterized in that an applied layer is formed by using a transparentconductive layer forming application liquid mainly composed ofconductive oxide particles and a binder on said transparent plastic filmsurface and then, a second applied layer is formed on a back face (faceon which the applied layer is not formed) of the transparent plasticfilm on which the applied layer is formed by using the transparentconductive layer forming application liquid mainly composed of theconductive oxide particles and the binder and then, forming atransparent conductive layer and a second transparent conductive layerby applying compression processing to the transparent plastic film onwhich the applied layer and the second applied layer are formed and thencuring the compressed layer.
 13. The method for manufacturing adispersion-type electroluminescent element according to claim 12,wherein said compression processing is carried out by rolling processingof metal rolls.
 14. The method for manufacturing a dispersion-typeelectroluminescent element according to claim 13, wherein said rollingprocessing is carried out with a linear pressure: 29.4 to 490 N/mm (30to 500 kgf/cm).
 15. The method for manufacturing a dispersion-typeelectroluminescent element according to claim 12, wherein on a faceopposite to a face of a transparent plastic film with said transparentconductive layer or said transparent conductive layer and a secondtransparent conductive layer formed, on which a dispersion-typeelectroluminescent element is formed, a release liner film (liner filmthat can be peeled off) on which a weak pressure-sensitive adhesive isapplied is bonded and then, the dispersion-type electroluminescentelement is formed and further, the release liner film is peeled off andremoved.